1. Field of the Invention
This invention relates to a method of hydrotreating shale oil. More particularly it relates to the catalytic treatment of crude shale oil with hydrogen under specified conditions whereby the amount of jet fuel produced per barrel of shale oil is substantially greater than by conventional methods.
2. Description of the Prior Art
Crude shale oil contains nitrogen containing compounds and impurities such as arsenic, compounds of arsenic, iron and compounds of iron. Both the nitrogen compounds and impurities are desirably removed or at least minimized in the final shale oil product. While sulfur and oxygen containing compounds are also present, treatment of the oil by hydrogen will reduce the amount present in the oil.
Crude shale oil produced by thermal means also contains organic compounds having unsaturated hydrocarbon bonds such as olefinic and diolefinic bonds. The unsaturation is undesirable because of possible problems it can cause in processing and in the final shale oil product.
Shale oil is obtained from oil shale which is indigenous in large quantities within the continental United States. Its availability can insure that the United States armed forces have sufficient hydrocarbon fuel, particularly, jet fuel, e.g., JP-4, for its national defense.
Thus it is imperative that crude shale oil be easily and relatively inexpensively processed whereby the nitrogen compounds and impurities are removed, the unsaturated carbon bonds saturated, and a large percent of the crude shale oil converted to jet fuel.
U.S. Pat. No. 3,779,903, G. S., Levinson, Dec. 18, 1973 discloses a catalytic hydrodenitrification of shale oil at a temperature of 250.degree.-480.degree. C. (482.degree. F.-896.degree. F.), 100-5000 psig, LHSV (volume of feed/volume of catalyst/hour) 0.1-10 and H.sub.2 /oil, SCF/BBL of 200-15,000. The catalyst contains oxides of nickel, molybdenum, tungsten, cobalt and mixtures thereof. U.S. Pat. No. 3,850,746, H. E. Robson, Nov. 26, 1974 discloses catalytic hydrodenitrification of hydrocarbon feedstocks at pressures ranging from about 500 psi to about 2000 psi, hydrogen gas rates ranging from about 1000 SCF/BBL to about 10,000 SCF/BBL and a superficial liquid hourly space velocity, LHSV, ranging from about 1 to about 5 with temperatures generally ranging from about 350.degree. C. (662.degree. F.) to about 390.degree. C. (734.degree. F.) at start-of-run conditions and from about 390.degree. C. to about 430.degree. C. (806.degree. F.) at end-of-run conditions. The catalyst is a chrysotile catalyst combined with a hydrogenation component selected from Group VIB, Group VIIB and Group VIII metals; representatives of these metals include nickel and molybdenum. U.S. Pat. No. 3,717,571, B. L. Schulman, Feb. 20, 1973 discloses two stage hydrogenation for raw shale oil. The operating conditions for the stages are as follows:
______________________________________ First Stage Second Stage ______________________________________ Temperature .degree.F. 650 to 800 600 to 750 Pressure, psig 1000 to 4000 1000 to 4000 LHSV, w/hr/w 0.1 to 3.0 0.1 to 3.0 H.sub.2 treat rate, SCF/BBL 5000 to 30,000 5000 to 30,000 Catalyst, e.g., CoMo on Al.sub.2 O.sub.3 CoMo on Al.sub.2 O.sub.3 ______________________________________
U.S. Pat. No. 4,133,745, D. K. Wunderlich, Jan. 9, 1979 discloses fractioning raw shale oil into a naphtha cut and a gas oil cut. The naphtha cut (350.degree. F., end point), along with a second naphtha cut (450.degree. F., end point) obtained from hydrotreating the gas oil cut, is midly hydrotreated (compared to the gas oil cut). The gas oil cut is first subjected to an impurity removal step prior to its severe hydrotreatment (compared to the naphtha) at 750.degree. F., 2000 psig and whsv of 2.4, for example. The impurity removal step can consist of treatment with a calalyst designed for the removal of such impurities on the catalyst, caustic treating, and so forth as is known in the art, as disclosed more particularly in U.S. Pat. No. 3,954,603, D. J. Curtin, May 4, 1976.
However, none ot the prior art suggests applicants' particular operating conditions whereby the result is the making of a relatively large amount of jet fuel from crude shale oil.